Transcriptional heterogeneity of catabolic genes on the plasmid pCAR1 causes host-specific carbazole degradation.

To elucidate why plasmid-borne catabolic ability differs among host bacteria, we assessed the expression dynamics of the Pant promoter on the carbazole-degradative conjugative plasmid pCAR1 in Pseudomonas putida KT2440(pCAR1) (hereafter, KTPC) and Pseudomonas resinovorans CA10. The Pant promoter regulates the transcription of both the car and ant operons, which are responsible for converting carbazole into anthranilate and anthranilate into catechol, respectively. In the presence of anthranilate, transcription of the Pant promoter is induced by the AraC/XylS family regulator AntR, encoded on pCAR1. A reporter cassette containing the Pant promoter followed by gfp was inserted into the chromosomes of KTPC and CA10. After adding anthranilate, GFP expression in the population of CA10 showed an unimodal distribution, whereas a small population with low GFP fluorescence intensity appeared for KTPC. CA10 has a gene, antRCA, that encodes an iso-functional homolog of AntR on its chromosome. When antRCA was disrupted, a small population with low GFP fluorescence intensity appeared. In contrast, overexpression of pCAR1-encoded AntR in KTPC resulted in unimodal expression under the Pant promoter. These results suggest that the expression of pCAR1-encoded AntR is insufficient to ameliorate the stochastic expression of the Pant promoter. Raman spectra of single cells collected using deuterium-labeled carbazole showed that the C-D Raman signal exhibited greater variability for KTPC than CA10. These results indicate that heterogeneity at the transcriptional level of the Pant promoter due to insufficient AntR availability causes fluctuations in the pCAR1-borne carbazole-degrading capacity of host bacterial cells.IMPORTANCEHorizontally acquired genes increase the competitiveness of host bacteria under selective conditions, although unregulated expression of foreign genes may impose fitness costs. The "appropriate" host for a plasmid is empirically known to maximize the expression of plasmid-borne traits. In the case of pCAR1-harboring Pseudomonas strains, P. resinovorans CA10 exhibits strong carbazole-degrading capacity, whereas P. putida KT2440 harboring pCAR1 exhibits low degradation capacity. Our results suggest that a chromosomally encoded transcription factor affects transcriptional and metabolic fluctuations in host cells, resulting in different carbazole-degrading capacities as a population. This study may provide a clue for determining appropriate hosts for a plasmid and for regulating the expression of plasmid-borne traits, such as the degradation of xenobiotics and antibiotic resistance.

Colonic Endoscopic Submucosal Dissection for a Granular Cell Tumor with Insufficient Endoscopic Manipulation in the Hepatic Flexure.

This report describes a granular cell tumor (GCT) with insufficient endoscopic manipulation in the hepatic flexure (HF) of the colon, which was treated by endoscopic submucosal dissection (ESD) using a splinting tube and the spring S-O clip traction method. A 44-year-old man presented with a 10 mm subepithelial tumor in the HF near the ascending colon on colonoscopy. The lesion had a smooth surface without erosion. The histology of biopsied specimen from the lesion was suspected as a GCT. Most GCTs are considered low-grade malignant, but ESD was chosen to treat the lesion due to the patient's insistence on endoscopic treatment. Because the lesion was located in the HF, it was assumed that the scope manipulation during ESD would be difficult. During ESD, a splinting tube was utilized to stabilize endoscopic manipulation and the spring S-O clip traction method to keep clear visualization of the submucosa, and the procedure was completed without adverse events. An 8 × 7 mm lesion with negative margins was removed by ESD. Hematoxylin and eosin staining showed atypical cells with round-to-oval nuclei and acidophilic vesicles, and immunohistochemical staining for S-100 protein was strongly positive with a Ki-67 labeling index of 5%. The lesion was pathologically confirmed as a GCT. This case showed the usefulness and safety of ESD for GCT with insufficient endoscopic manipulation in the HF.

Esophageal achalasia with severe malnutrition and liver enzyme elevation.

A 70-year-old woman presented dysphagia and postprandial vomiting, and weight loss of about 15 kg in one year. She was markedly emaciated with a body mass index of 12.4 kg/m2 and had difficulty in movement. Esophagogastroduodenoscopy and computed tomography revealed stenosis of the esophagogastric junction (EGJ) with no malignant findings. Additionally, based on the findings of the esophagogram and high-resolution manometry, the patient was diagnosed with esophageal achalasia. The patient also had an elevation in liver enzymes but was ruled out alcoholic, drug-induced, viral, or other hepatitis. It was considered that malnutrition caused by esophageal achalasia led to a rise in liver enzymes. After the onset of nutritional therapy, the liver enzyme elevation deteriorated, electrolyte abnormalities and hypoglycemic attacks occurred frequently. She had developed the refeeding syndrome, thus feeding was reduced, but the condition deteriorated further and the liver enzymes reached a peak. These findings were assumed to be due to persistent malnutrition, and normalized with gradually increased nutrition. After improving the general condition, per-oral endoscopic myotomy (POEM) was performed. After POEM, her dysphagia disappeared and nutritional state completely improved. Careful nutritional therapy improved her general condition, and POEM improved gastrointestinal symptoms and prevented the recurrence of malnutrition.